The operation of the Fast Reactor is considered in terms of normal equilibrium conditions and normal shut-down. The proposed loading, control rod adjustment and subsequent "floating" operation are discussed. Safety devices and interlocks are described. Temperature and reactivity changes are examined with respect to various system failures, phase changes, and "flashing" of the reactor. Slow changes due to faulty slug cooling are also considered. The calculations were initially based upon 10 kw operation. Performance tests of the mercury system now indicate that 20-kw operation may be feasible. (D.E.B.)

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This progress report discusses activities of the P Division for the month of April, 1948. The D and F Piles operated at 275 megawatts throughout April except for scheduled outages. Each operating area had an extended outage to remove a portion of the brick from the wall which runs across the rear edge of the top of the unit and to replace the vertical neoprene seal between the front face and the experimental side shields. This program described in detail under Mechanical Experience. The B-Pile was maintained in standby condition with a water flow of 10,150 gallons/minute. The 100 Area discharge rate continued at 60 tons per month. The exclusive use of lead dipped 4 inch slugs fabricated from alpha rolled or alpha extruded metal was started effective April 1. Work was stated April 12 in the 300 Area on a program of decanning 160 tons of 8 inch gamma extruded triple-dip canned pieces which were not considered good risks for pile operation. The slug recovery operation was placed on a 2 shift per day schedule on April 19 to expedite this work so that the metal can be recast and rolled at the earliest moment. The 300 Area canning …

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